You can set expectations as high as you like, but surely there has to be a sense of realism about it when you do so.
The reality of the situation, is that under this board and as of now in the premier league, we cannot compete on a financial basis with the top 6 teams of United, City, Chelsea, Liverpool, and Arsenal. They have far more money than us, and as such can afford to have expensive failures as players and to fork out top $$$ for the best every year when things aren't going their way.
In order to compete on a level playing basis, either we need the board to make an investment of new capital into the playing staff (not going to happen), or we need to carefully and cannily build a team that can match those players. Not only just build a team but also keep the core group together over a longer period of time.
Even then achieving top 4 is a very tough ask because of the financial limitations on the club, let alone doing it consistently.
As of now we currently have some players who would not look remiss in a top four team, but lack the quality in depth to play at a top 4 level consistently when players are out injured and the squad is stretched. In order for this current team to achieve top 4 we'd be looking at a team playing very well, with injury luck and some bad luck on behalf of our competitors.
The manager for me has done a really good job in building a young squad with a high ceiling. Whether they will stay together long enough to reach that ceiling with us is unlikely unless we find some level of success as a group in this season.
He had one great year in which we genuinely challenged the top four, and on any other year might well have attained it. He had one poor year where we really underperformed (with perhaps some significant confounding factors).
For me anyway this is the year for him to prove that the first year wasn't a fluke and that we can compete at the top table under him.
TLdr People expecting us to get top four regularly are off their medication. Roberto has this season to prove we can compete for Europe under him.